1. Field of the Invention
The present invention relates to exhaust outlets forming the end zone of an internal combustion engine exhaust gas line.
Exhaust outlets are generally intended to be connected to the outlet of an exhaust gas conduction duct, for example the outlet of the silencer, and they comprise an inlet orifice with means for connection to the exhaust gas conduction duct and an outlet orifice open to the free air for discharge of the gases, and means for conducting the gases from the inlet orifice to the outlet orifice.
In their simplest form, exhaust outlets are formed by a simple tube.
2. Description of the Prior Art
An older but more elaborate form of exhaust outlet is described in the document FR-A-606 040. It comprises a pipe with several successive bell-mouth portions surrounded by an outer casing. Each bell-mouth portion is pierced in its upper part to allow the exhaust gases to pass through the gap between the pipe and the outer casing. In this gap, the gases follow a spiral movement and leave through lower openings in the casing, directed towards the ground. The exhaust noise is attenuated, condensates form in the gap between the pipe and the casing and are discharged through the lower openings with the gases.
Exhaust outlets are subjected to chemical and physical stresses and aggressions such as the ambient humidity, the heat of the exhaust gases, the liquid or solid particles carried along by the exhaust gases. The result is a risk of fairly rapid corrosion of the exhaust outlets. This risk is all the greater in the case of a structure such as described in the document FR-A-606 040, for the corrosion develops in the vicinity of each lower opening and in the gap through which the gases flow.
Attempts have been made to reduce such corrosion by providing exhaust outlets made from an anti-corrosion material such as stainless steel. An exhaust outlet made from such material, when it is new, has a bright pleasant appearance to the eye. However, during use, the appearance is rapidly impaired because particles brought by the exhaust gases are deposited on the exhaust outlet in the vicinity of its outlet orifice. Furthermore, the condensation liquids which form inevitably in the exhaust outlet tend to drip towards the outside through the outlet orifice and accentuate the external cleanliness defects of the exhaust outlet.